(1) Field of the Invention
The present invention relates to a technique for renting a storage medium which stores digital content.
(2) Description of the Related Art
Storage mediums such as DVDs for digitally storing a work including movies and music have become increasingly widespread. High-volume information can be digitally stored in such storage mediums as DVDs and can be used semi-permanently.
By taking advantage of such storage mediums, a rental-service business for renting storage mediums which store movies, music, etc., has been developed to create a huge market.
Japanese Laid-open Patent Application No. H11-164238 discloses the following technique which is aimed at billing users economically in accordance with the reproduction conditions of a work. At a rental shop, a user selects, from a group of discs, a disc which stores information that the user wants. At the rental shop, information pertaining to the selected disc, such as a serial number, a catalogue number, a specified reproduction time, and a reproduction number (=0), is written to an IC card that is owned by the user. The user plays the disc by using a player to reproduce the information stored therein. Here, a reproduction time is measured and accumulated. When the accumulated reproduction time exceeds the specified reproduction time, the reproduction number, which is the number of times the disc is played, is counted as one. The user may play the disc a plural number of times, and the counted reproduction number is written to the IC card. When the user returns the disc and the IC card, data in the IC card is read at the rental shop and an amount of payment is calculated in accordance with the reproduction number.
Also, Japanese Laid-open Patent Application No. H11-167768 discloses the following technique which is aimed at managing a rental time limit so that a rented disc can be played only within a rental-use period for the disc. At a rental shop, a user selects, from a number of discs, a disc which stores software information that the user wants. Each disc also stores its unique management information. Information pertaining to the selected disc, i.e., unique management information and rental-use time limit information of the selected disc, is written to an IC card by an IC card writing apparatus. Then, the user is given this IC card together with the selected disc. The user brings home the disc and the IC card, and sets them on a special player. The player can play the disc only within the rental-use period that is written in the IC card.
Moreover, Japanese Laid-open Patent Application No. 2002-50126 discloses the following technique which aimed at providing, at low costs, a reproduction apparatus that prevents reproduction of data in a storage medium whose rental time limit is expired, a storage medium, and a rental system. A data reproduction apparatus is equipped with a data reproduction control unit. The data reproduction control unit starts clocking time with an initial value being the start date and time of a reproduction-allowed period shown by management information. The reproduction-allowed period is a time period during which data is allowed to be reproduced. The data reproduction control unit allows the data to be reproduced until the kept date and time reaches the end date and the time of the reproduction-allowed period. The rental system of this invention includes a data writing apparatus which writes, to a storage medium, data and its management information showing a reproduction-allowed period during which the data is allowed to be reproduced, the storage medium which stores the data and the management information, and the above-described data reproduction apparatus.
Further, Japanese Laid-open Patent Application No. 2002-149061 discloses the following technique which is aimed at providing a distribution system and a distribution method that improve user convenience, eliminate profit loss of a merchant, and realize secure content protection in the field of digital content distribution. Mutual authentication is performed between a reproduction apparatus and an IC card and also between the IC card and a management center. The IC card transmits, to the management center, a certificate of a reproduction apparatus public key that has been received from the reproduction apparatus. A user inputs, using a terminal, contract information including a content title and a rental period. The management center receives the contract information to which a signature of the IC card is added, encrypts a content encryption key and the like using the reproduction apparatus public key and the like, adds a signature to the encrypted data, and transmits the data with the signature to the terminal. The terminal writes the transmitted data to the IC card. When the signature matching succeeds, the terminal stores the content into the storage medium. The reproduction apparatus decrypts the encrypted content encryption key received from the IC card, and decrypts the content by using the content encryption key.
There are increasing demands from rental agents that rent storage mediums which store movies, music, etc. for effectively limiting the users' use of work stored in such storage mediums.